Also called: second cervical vertebra, C2
The axis is the second cervical vertebra (C2). Its distinctive feature is the dens, or odontoid process, a tooth-like projection that rises from the body and forms a pivot for the atlas. This pivot allows the head to rotate from side to side.
| Type | Irregular bone (vertebra). |
|---|---|
| Location | Second bone of the vertebral column, below the atlas. |
| Landmarks | Dens, body, spinous process, superior articular facets, transverse processes. |
| Articulations | Atlas (atlanto-axial joints) and C3 vertebra. |
| Muscle attachments | Obliquus capitis inferior, rectus capitis posterior major, longus colli, semispinalis cervicis. |
3D model: BodyParts3D (CC BY 4.0), adult male reference anatomy. Highlighted structure shown with nearby bones for context.
The alar and transverse ligaments hold the dens in position against the anterior arch of the atlas.
A tooth-shaped projection from the body of C2 that acts as the pivot for rotation of the atlas and head.
Rotation of the head, as in shaking the head to say no.
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